For the family of Army Sgt. Mark Cofield, the war in Iraq is far from over.

"Mark was my rock," Mark' s sister, Sara Cofield, said in an interview with the Colorado Springs Gazette. "He was my brother, he was my world. He raised me."

She said it hurt to breathe when she found out that her brother had been killed in Baghdad last month.

Cofield, 25, died July 17 from injuries sustained in a non-combat related incident, according to icasualties.org. He was the latest of 57 American troops to die in Iraq in the year sincethe United States formally ended its combat mission there and just months before the scheduled withdrawal of all its troops.

In 2011 alone, 44 U.S. troops have died, according to icasualties.org, an independent group that tracks American casualties in Iraq and Afghanistan. They included four other U.S. soldiers who also lost their lives in July, all on the battlefield. In June, the U.S. suffered its deadliest month in Iraq since 2008, with 15 service members dying.

End of combat?
Officially, U.S. combat operations ended in Iraq on Aug. 31, 2010, two weeks after all combat troops left the country on Aug. 18, 2010. Operation Iraqi Freedom led to the overthrow of dictator Saddam Hussein's regime but now has lasted more than eight years and left more than 4,400 U.S. troops and tens of thousands of Iraqis dead.

At the time of the pullout, President Barack Obama released a statement calling the troops' withdrawal a "milestone in the Iraq war."

At the height of U.S. involvement, nearly 250,000 troops operated throughout the country, while by the end of August 2010, around 50,000 Americans remained in the country in a non-combat role.

But that non-combat role is a constantly evolving one.

U.S. forces continue to battle militants
The U.S. military carried out two unilateral air strikes in Iraq in June that did not involve Iraqi forces, both of them in self-defense to prevent attacks, the main U.S. military spokesman in Iraq said.

The airstrikes are another sign of how the United States is being forced to sometimes respond directly to militant threats even a year after it formally ended its combat mission.

The United States is due to withdraw all of its 46,000 forces from Iraq by the end of the year unless negotiations with Baghdad end with an agreement to keep some forces there on a slimmed-down training mission.

Legally binding guarantees for remaining U.S. forces are expected to be part of any such deal, but whether that will include the right for U.S. forces to defend themselves is unclear.

Although violence in Iraq is down from the height of the sectarian killings in 2006-07, a spate of recent attacks has shown that the militant threat could still pose a serious challenge to Iraqi forces if all U.S. troops depart.

Suicide bombers, car bombs and roadside explosives hit more than a dozen Iraqi cities and towns on Monday, killing around 70 people, in the highest number of killings on a single day in Iraq this year.

The U.S. expressed concern at the surge of violence just months before the scheduled withdrawal, The New York Times reported.

"The Iraqis themselves have more capacity than they did have, but they've got to exercise it," said Secretary of State Hillary Rodham Clinton, according to the Times.

Photos: Bomb blasts across Iraq

Residents inspect a damaged church after a bomb attack in central Kirkuk, on Monday, August 15, as scores of people were killed across the country in a spate of nationwide violence, just months ahead of a pullout of US forces. A parked car bomb and a motorcycle bomb killed one person and wounded 12 others in central Kirkuk.
(Ako Rasheed / Reuters)
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Iraqi security forces inspect damages after two car bombs, one of which was detonated by a suicide attacker, detonated in the holy Shiite city of Najaf, on Monday.
(Qassem Zein / AFP - Getty Images)
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Residents gather at the site of bomb attacks in Kut, 93 miles southeast of Baghdad, on Monday. Two bombs tore through a public square in the southern Iraqi city of Kut, killing at least 37 people in the worst in a string of bombings and suicide attacks across the country, officials said.
(Stringer/iraq / Reuters)
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Iraqi security forces inspect the site of a suicide car bomber plowed his vehicle into a checkpoint outside a police building just outside the holy city of Najaf on Monday.
(Alaa Al-marjani / AP)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.